Hats On!

Ozone depletion is cause for caution, but it's no reason to stay barricaded indoors or put on an astronaut suit before venturing outside. Excessive exposure to the sun's ultraviolet (UV) rays has always been dangerous; the ozone problem just adds to the risk. Says NASA's Michael Kurylo: "We're not talking about a single exposure to a death ray. It takes repeated exposure over long periods of time."

Even if there were no atmospheric damage, an estimated one-sixth of all Americans would still develop skin cancer during their lifetime. Most cases are curable, if detected early. The 4% to 8% loss of...